The National Football League, or NFL, has announced that it will fine teams if their players fail to stand during the playing of the national anthem.

Instead, players who do not wish to stand can wait in the locker room until the song is over.

The NFL announced the new policy Wednesday. NFL team owners approved the measure. The league did not say how much it would fine a team if a player does not follow the new rules.

The “Star-Spangled Banner” is played before the start of each football game. Last season, some NFL football players chose to get down on one knee as the during the anthem instead of standing. The move was in protest of police shootings of unarmed black men in the United States.

The majority of NFL players are African American.

Some football fans, and even US President Donald Trump, criticized the players for appearing unpatriotic.

Last year, Trump used social media to demand an end to the players’ protests. In a tweet last October, for example, Trump asked whether the NFL should get money-saving tax breaks if its players continue, in his words, “disrespecting our anthem, flag and country.”

Trump also pushed the league to punish players who protest. The NFL last year rejected the president’s calls.

The NFL Players Association, or NFLPA, is a union for NFL players. It said the league did not seek its help in creating the new policy. In a statement,The union aims to protect the rights and interests of NFL players.

In a statement, the NFLPA said it would examine the policy and challenge any part of it that does not meet “collective bargaining agreements.”

The union added that NFL players demonstrate their patriotism in many ways, including, it said, “through their protests to raise awareness about the issues they care about.”